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Subject[PATCH] x86/mpx/selftests: Fix wrong bounds with old _sigfault
Date
I fixed this on my machine and forgot to tell anyone until a
recent bug report. The patch almost get lost. Archiving it here.

For distributions with old userspace header files, the _sigfault
structure is different. mpx-mini-test fails with the following
error:

[root@Purley]# mpx-mini-test_64 tabletest
XSAVE is supported by HW & OS
XSAVE processor supported state mask: 0x2ff
XSAVE OS supported state mask: 0x2ff
BNDREGS: size: 64 user: 1 supervisor: 0 aligned: 0
BNDCSR: size: 64 user: 1 supervisor: 0 aligned: 0
starting mpx bounds table test
ERROR: siginfo bounds do not match shadow bounds for register 0

Fix it by using the correct offset of _lower/_upper in _sigfault.
RHEL needs this patch to work.

Fixes: e754aedc26ef ("x86/mpx, selftests: Add MPX self test")
Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
tools/testing/selftests/x86/mpx-mini-test.c | 27 +++++++++++++++++++++++++--
1 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/x86/mpx-mini-test.c b/tools/testing/selftests/x86/mpx-mini-test.c
index ec0f6b4..45035c3 100644
--- a/tools/testing/selftests/x86/mpx-mini-test.c
+++ b/tools/testing/selftests/x86/mpx-mini-test.c
@@ -315,11 +315,34 @@ static uint64_t read_mpx_status_sig(ucontext_t *uctxt)
return si->si_upper;
}
#else
+
+/* This deals with old version of _sigfault in some distros
+old _sigfault:
+ struct {
+ void *si_addr;
+ } _sigfault;
+
+new _sigfault:
+ struct {
+ void __user *_addr;
+ int _trapno;
+ short _addr_lsb;
+ union {
+ struct {
+ void __user *_lower;
+ void __user *_upper;
+ } _addr_bnd;
+ __u32 _pkey;
+ };
+ } _sigfault;
+*/
static inline void **__si_bounds_hack(siginfo_t *si)
{
void *sigfault = &si->_sifields._sigfault;
void *end_sigfault = sigfault + sizeof(si->_sifields._sigfault);
- void **__si_lower = end_sigfault;
+ int *trapno = (int*)end_sigfault;
+ /* skip _trapno and _addr_lsb */
+ void **__si_lower = (void**)(trapno + 2);

return __si_lower;
}
@@ -331,7 +354,7 @@ static uint64_t read_mpx_status_sig(ucontext_t *uctxt)

static inline void *__si_bounds_upper(siginfo_t *si)
{
- return (*__si_bounds_hack(si)) + sizeof(void *);
+ return *(__si_bounds_hack(si) + 1);
}
#endif

--
1.7.5.4
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